FETAL BLOOD CIRCULATION
* Placenta - Organ of gas exchange
Pattern of blood flow:
Placent —highly oxygenated blood→ Umbilical vein (arises from internal iliac vein) → divides into left, right umbilical veins.
Left umbelical vein → Portal vein → liver → hepatic vein → IVC (containe deoxygenated blood from lower limbs) → Right atrium.
only if the pressure of blood ↑↑
Right umbilical vein → ductus venosus (bypass liver) → IVC → right atrium. mixed blood (high O₂ const.)
Right atrium —via foramen ovale→ left atrium
* Small amount of blood from right atrium enters right ventricle → Pulmonary art. → lungs.
left atrium → left ventricle → Aorta ← via ductus arteriosus → because of pressure
Aorta → Systemic circulation (R. L. common iliac arteries) → Umbilical arteries 2 → Placenta.
Remnant structures after birth:
- 1. Ductus Arteriosus: After birth closes becoming the ligamentum arteriosum 9 ~ 12-24 hours.
- 2. Foramen Ovale : " " " forming the fossa ovalis in the right atrium of adult heart.
- 3. Ductus venosus : " " " ligamentum venosum of the liver.
- 4. Umbilical Arteries & veins : " " arteries → medial umbilical ligament; vein → Round ligament of the liver.
mixed blood the organs use the oxygenated blood & pass the deoxygenated blood.